Episodic memory and the hippocampus: it's about time

Several recent studies have sought to develop animal models of episodic memory, the capacity to recollect unique personal experiences. However, these studies have not yet provided unambiguous evidence that this capacity is based on recollection of the learning episodes. A recent study that examined memory for the ordering of events within unique experiences, and demonstrated a critical and selective role for the hippocampus, suggests a new and promising model for neurobiological analyses of episodic memory.     

Development of executive attention in preschool children

The development of self-regulatory systems during the preschool years is accompanied by a dramatic increase in the ability to inhibit actions based on the directions of others. Several tasks have shown evidence of changes in self-regulation during the fourth year of life. The current cross-sectional study used a Simple Simon task, in which 33 3- to 4-year-old children were asked to respond to the command of one large toy animal but not to the command of another. Three important aspects of self-regulation were examined: the ability to inhibit action in the face of conflict, error detection/correction and the use of verbal and physical control strategies. The ability to inhibit a response in this task increased from 22% to 90% between 36 and 48 months of age. Post error slowing of Reaction Time (RT) indicative of error detection emerged at about the same age as successful inhibition. Physical rather than verbal self-regulation strategies were spontaneously employed by children to aid in the process of inhibition.     

Depth inversion despite stereopsis: the appearance of random-dot stereograms on surfaces seen in reverse perspective.

Inside-out relief masks of faces can be depth-inverted (i.e. seen in reverse perspective) during close-up binocular viewing. If a random-dot stereogram is projected onto such a mask, stereopsis can be achieved for the stereogram, and its depth planes are correctly seen while the mask itself, including the region covered by the stereogram, is simultaneously perceived as depth-inverted. This demonstration shows that binocular depth inversion cannot be explained by a complete loss of stereoscopic information (e.g. through monocular suppression), or by a process analogous to pseudoscopic viewing whereby retinal disparities are incorporated into perception, but with their signs uniformly reversed.